1. Technical Field
The present invention relates to a piezoelectric element which includes a first electrode, a piezoelectric layer, and a second electrode, and a piezoelectric element applied device which includes the piezoelectric element.
2. Related Art
Generally, a piezoelectric element includes a piezoelectric layer and two electrodes. The piezoelectric layer has electromechanical conversion characteristics. The piezoelectric layer is interposed between the two electrodes. A device (piezoelectric element applied device) which uses such a piezoelectric element as a driving source has been recently actively developed. As one of the piezoelectric element applied device, for example, a liquid ejecting head represented by an ink jet recording head, a MEMS element represented by a piezoelectric MEMS element, an ultrasonic measurement device represented by an ultrasonic sensor and the like, and a piezoelectric actuator device are provided.
As one of materials (piezoelectric materials) of a piezoelectric layer of a piezoelectric element, potassium sodium niobate (KNN; (K, Na)NbO3) has been proposed (for example, see JP-A-2008-159807 and Japanese Patent No. 4735840). In Japanese Patent No. 4735840, the piezoelectric layer is formed by using a solution method, and thus productivity is improved.
However, a KNN thin film which realizes at least one of improvement of piezoelectric characteristics and suppression of occurrence of a leakage current is required.
If the KNN thin film is formed by using the solution method in which high productivity is possible, there is a problem in that a void is easily generated, and the void influences the piezoelectric characteristics and the occurrence of a leakage current. Because the piezoelectric characteristics may be deteriorated by suppressing the occurrence of the void, realization of improving the piezoelectric characteristics is not possible even by suppressing the occurrence of the void.
Such a problem is not limited to a piezoelectric element used in a piezoelectric actuator which is mounted in a liquid ejecting unit represented by an ink jet recording head, and similarly also occurs in a piezoelectric element used in other piezoelectric element applied devices.